Test approximately 80 substances to be supplied by the NCI, for mutagenicity in a blind study. The substances will be tested using Salmonella typhimurim strains TA-98, TA-100, TA-1535, TA-1537, and TA-1538, Esherichia coli strains WP-2/uvrA-and @3110/polA+ and p3478/polA-.